Process for concentrating phosphate ores



Patented Dec. 1, 1942 UNITED STATES PATENT OFFICE No Drawing. Application April 25, 1940,

-- Serial No. 331,528

7 Claims. (Cl. 209-160) This invention relates to a process for concentrating phosphate ores, and particularly concerns the more eflicient utilization of oil-soluble waterinsoluble petroleum sulfonates in the flotation of the bone phosphate of lime constituent of fine phosphate ores. Oilsoluble water-insoluble petroleum sulfonates, in a neutralized condition, are at present available at reasonable prices under various designations including the name mahogany soaps"; and the term "mahogany soaps, wherever used in this specification and in the claims hereto appended, means oil-soluble waterinsoluble petroleum sulfonates produced in the course of sulfuric acid treatments of petroleum distillates. The term mahogany soaps" as herein used, of course does not include all sulfonated petroleum oils, and particularly does not include the water-soluble petroleum sulfonic acids, sometimes called green oils" and acid sludges which are also produced in the course of sulfuric acid treatments of petroleum distillates.

In attempting to utilize mahogany soaps for phosphate flotation we found that, although these reagents exhibit a definiteselective action toward phosphate and act as phosphate collectors, they are ineflicient and unsatisfactory for a practical recovery operation when used in the usual manner known to the art of concentrating phosphate with fatty acid soaps, resin acid soaps or other soaps in conjunction with a frothing agent and an inert oil such as fuel oil. The use of mahogany soaps along with a frothing agent such as pine oil and an inert oil such as fuel oil produces pulps that are very slow in floating and from which we were unable to obtain recoveries high enough for a practical separation. In following these usual procedures, we also found that the reagent consumption per ton of phosphate concentrates produced was abnormally high and consequently uneconomical.

One of the difliculties encountered in the use of mahogany soaps for phosphate flotation is that of converting the same to a proper state of dispersion. When insufficiently dispersed the floating properties of the neutral oil are not fully utilized and the same are less satisfactory than even hereinbefore noted. One way of obtaining the proper dispersion of these reagents in water is to boil one part of the mahogany soap and from 10 to 20 parts of water for a period of about ten minutes. If the water is reduced below these proportions the dispersion jells on cooling and is unsuitable for use. The necessity of heating such a relatively large proportion of water for the neutral oil is a detrimental factor to practical operation of the process.

The primary object of the invention is to provide several ways of improving the efliciency and capability of mahogany soaps, or the neutral oils noted, in phosphate flotation operations to such a point as to make the same desirable and practical reagents for this purpose.

Another object of the invention is to obviate the use in this connection of the dilute water dispersions above described.

One phase of our invention resides in the discovery that small additions of a fatty acid and/or a resin acid to the combination of a neutral mahogany soap and fuel oil, with or without pine oil, have a remarkable effect on the flotation of phosphate with these reagents. Thus, with additions of about 0.5 pound per ton of ore of fish oil fatty acids and/or a mixture of fatty and resin acids known as Liqro" 0r Talloil we have recovered from 133% to 717% more phosphate in the floated concentrates. We also found substantial increases in the rate or speed with which the phosphate floats when the noted acid additions are utilized. The improvement effected in the efliciency of the mahogany soap reagent in the combination makes the same commercially practical for phosphate flotation.

Another important advantage of our described addition of fatty and/or resin acids to flotation ore pulps, along with mahogany soap collectors and fuel oil and a frothing agent, such as pine oil, is that we find it is not necessary to use dilute water dispersions of the mahogany soap reagent when such acid additions are made to a mixture of the petroleum sulfonates and the oils before these reagents are mixed into the phosphate ore pulp to be concentrated. Such mixtures of fatty and resin acids, or either of the same, mahogany soap, fuel oil and a frother such as pine oil, float the phosphate just as efliciently and more rapidly than 340% dispersions of the mahogany soap in water together with the same proportions of assisting reagents. This discovery eliminates a very troublesome handling problem in a practical plant operation, because the large volumes of water required for the dilute dispersions of the mahogany soaps do not have to be handled and heated.

A second phase of our invention resulted in the discovery that the addition of very small amounts of alkali to the phosphate pulps during the mixing in of the above described reagents still further increased the efficiency of these reagents. In practice of this phase of our invention, we obtained equal recoveries of phosphate with from A; to ,5 of the amounts of mahogany soap oil, inert fuel oil, pine oil, and fatty and/or resin acids by the addition of only 0.04-0.10 pound of sodium hydroxide per ton of heads. The practice of this second phase of our invention in conjunction with the first phase has enabled us to make very good recoveries of phosphate with use of extremely small amounts of the active mahogany soap, fuel oil, pine oil and fatty and/or resin acids, and with reagents which are easily and economically handled.

The inventors are aware that sulfonated petroleum oils have previously been suggested for phosphate flotation, and that separately therefrom fatty and resin acids in'coniunction with caustic soda have also been so used. It is, however, pointed out that the combination of the particular reagents herein employed is not disclosed in the prior art and that the process forming the present inventive concepts reduces the required amount and proportions of the reagents necessary for practical phosphate flotation iar below the minimum reagent requirements for ore separation taught in the prior art.

Several specific examples to illustrate the advantages of the invention herein disclosed, in practical operation of the same, follow.

In Table 1, shown on this page, comparisons are presented which indicate the eii'ect of small amounts of fatty and resin acids on phosphate flotation with dilute water dispersions of mahogany soap reagents. In test #1, 500 grams of a Florida phosphate debris, which had passed a 0.028" woven wire screen and been largely deslimed, was treated with the recorded amounts of mahogany soap oil, fuel oil and pine oil. The neutral mahogany soap reagent was a petroleum product supplied by the Sherwood Petroleum Company of Warren, Pennsylvania, under the designation Reagent 407 and is a. mahogany soap as herein'defined. Equivalent reagents are as hereinbefore noted, petroleum sulfonates, mahogany sulfonates and mahogany soap. This reagent was added to the pulp in a 3% water dispersion which was made by boiling the water and reagent together for 10 minutes. The reagents were mixed into the pulp for 4 minutes. The pulp was then diluted in a laboratory subaeration flotation cell of the impeller type, and aeration and agitation were continued until no further phosphate float rose to the surface. The float was continuously removed by means of a paddle. The results show very poor recovery of phosphate in the concentrates.

TABLE I The eflect of fatty and resin acids on phosphate flotation with dilute water dispersions of mahogany soap Roughing and cleaning flotations Roughing flotations Heads:

Weight in grams Per cent B. P. L Percent insol acid test #1 Without Reagents (lbs./ton

head

Mahogany soap Fuel Fish acid and talloiL. Pine oil Concentrates:

Rate (grams/minute) Per cent weig Per'cent B. P. L Per cent insol... Percent 13. P. L. re-

covery (Per cent increase in rec. Talillingsz per cent B. P.

In test #2, the procedure was the same except that 0.49 pound of a mixture of cod fish fatty acids and a talloil known as Liqro were added per ton of dry heads. No pine oil was used and the fuel oil was reduced as noted in the table. The recovery of phosphate in a rough concentrate of very good grade was 85.9%. The small addition of fatty and resin acids increased the phosphate recovery 237%.

Tests #3 and #4, in Table I, show a similar comparison on another sample of phosphate ore in which the rough concentrates from the first flotations were returned to the cell without further addition of reagents and re-floated to produce cleaned concentrates. In this case the addition of fatty and resin acids produced an excellent recovery of phosphate which was 133% greater than that obtained without th acid addition.

TABLE II The eflect of fatty and resin acids on phosphate flotation with oil mixtures of mahogany soap Roughing Roughing and cleanflotations ing flotations Heads:

Weight in grams 500 l, 000 Per cent 13. P. L. 36. 84 32. 67 Per cent insol.-. 57.07 68.02

Without With Without With acids acids acids acids test #5 test #6 test #7 test #8 Reagents (lbsJton head Mahogany soap-. 1. 24 l. 24 1. 00 1. 00 Fuel oil 1.86 1.86 1.50 1.50 Fish acid and/or talloil None 0.62 None 0.50 1. 24 0. 62 0. 70 0. 70

Concentrates:

Rate (grams/minute) 33 49 6 29 Per cent weight 16. 3 44. 4 5. 3 08. 1 Per cent B. P. L..--- 71.87 74.44 Per cent insol 10. 31 6. 45 Per cent B. P. L. re-

covery 31. 9 86. 8 l2. 1 86. 8 (Per cent increase in recovery) (272%) (717%) Tailings: per cent B. P. L. 8.86 7. 00

In the above Table II, comparisons are presented which show the eifect of small amounts of fatty and resin acids on phosphate flotation with mixtures of mahogany soap, fuel oil and pine oil. In these tests the same mahogany soap reagent was used, but it was added to the pulp as a mixture with the other oils and not as a dilute water dispersion. Otherwise, the procedure is the same as in the hereinbefore described tests #1 to #4. The test results of Table II show that the small additions of fatty and/or resin acids convert flotation failures into excellent separations. Phosphate recoveries are increased from 272% to 717%. The rate or speed at which the concentrates float is substantially increased. The results on tests #6 and #8, using oil mixtures of the mahogany soap reagent, compare favorably with those on tests #2 and #4 using dilute water dispersions of this reagent. Thus, in accordance with the teachings of our invention, it is unnecessary to use the mahogany soap reagent in dilute water dispersions to accomplish the desired result.

The effectiveness of the second phase of our invention is indicated in the test results in Table Table IV.

The eflect of small additions of alkali on phosphate flotation with oil mixtures of mahogany soap, fatty and resin acids, fuel oil and pine oil Roughing and cleaning flotations w ight in 1000 e grams Per cent B. P. L 32.67 Per cent insol 68. 02

Text #9 Test #10 Test 111 Test #12 Reagents (lbs./ton

heads):

Caustic soda None 0. 039 0. 116 0. 110 Mahoglany soap 1. 20 0. 74 0. 53 0. 40 Fuel l. 80 1. ll 0. 94 0. 60 Pine 01]..... 0. 84 0. 52 0.44 0. 28 Liam 0. 60 0. 37 0.32 0. 20

Ooncentra to minute) 26. 9 30. 2 45. 6 89. 6 Per cent we ht 38. 8 39. 3 41. 0 30. 0 Per cent B L.-. 74. 04 74. 22 74. 28 74. 67 Percentinsol 0.94 6.72 6.64 0.28 Per cent B. P. L. re-

covery 88. 0 89. 2 93. 1 90. 4 Percent B. P. 14.--..- 0.40 a so ass s. 20

Tests #10, #11 and #12 were made after mixing very small amounts of caustic soda into the pulp. This alkali was added to the pulp in the form of a. solution either at the beginning of the reagent mixing operation along with the other reagents or at some time during the mixing operation. The procedure which gave the best results was to mix the mahogany soap, fuel oil,

pine oil and Liam into a fairly dense pulp for about two minutes, then to add the caustic soda and continue mixing for about four minutes. Considering that the amount of caustic soda used in these tests was too small to cause any appreciable amount of soap," the results attained and noted in Table III were entirely at variance with that logically expected. Comparing the results of the last three tests with those of test #9, it is seen that equal or better recoveries of phosphate were obtained with from ;3 to of the reagents used in test #9. In test #12, the total organic reagents amount to only 1.48 pounds per ton of heads. This figure compares with 4.44 pounds of organic reagents used in test #9 and with from 4 to 5 pounds, which are the minimum requirements, used in the usual soap" phosphate flotation.

A comparison of the process of the present invention with similar amounts of the same reagents according to methods previously known in the art in this connection is contained in TABLE IV A comparison of the methods of the prior art with those of the present invention To: In Test :14 Test 115 rest #10 Test {'11 0. 0. 116 0. 116 None 200 0.333 None None 0433 0.117 0. 133 None 0. 154

um 0.100 0.167 0.190 0.3 8 None Concentrates: Per cent weight floated... 84.8% 40.9% 0.4% 1.0% None agents. Tests #15 and #16 show that no appreciable flotation is obtained when the sulfonated petroleum oil is left out, either with or without the pin oil, and with more of the assisting oils than in the first two tests. Test #17 shows, on the other hand, that considerably more mahogany soaps will not float the phosphate without the small additions of fatty acid and caustic soda.

-It will be understood that the foregoing description in no way limits the scope of our inventicn, and that changes in details can be made therein without departing from the spirit thereof. as set forth in the appended claims.

We claim as our invention:

1. A process of concentrating phosphate from an ore consisting principallyof phosphate and silica particles, comprising conditioning said ore inan aqueous pulp with a mahogany soap, a mixture of fatty and resin acids and a fuel oil, and then subjecting the thus conditioned pulp to a concentration process dependent on the surface characteristics of the ore particles as conditioned.

2. A process according to claim 1 in which an alkali is used with the other agents specified.

3. A process of concentrating phosphate from an ore consisting principally of phosphate and silica particles, comprising conditioning said ore in an aqueous pulp with a mahogany soap, a fatty acid and a fuel oil, and then subjecting the thus conditioned pulp to a concentration process dependent on the surface characteristics of the ore particles as conditioned.

4. A process according to claim 3, in which an alkali is used with the other agents specified.

5. A process of concentrating phosphate from an ore consisting principally of phosphate and silica particles, comprising conditioning said ore in an aqueous pulp with a mahogany soap, a resin acid and a fuel oil, and then subjecting the thus conditioned ore to a concentration process dependent on the surface characteristics of the ore particles as conditioned.

6. A process according to claim 5 in which an alkali is used with the other agents specified.

7. A process of concentrating phosphate from an ore consisting principally of phosphate and silica particles, comprising conditioning said ore in an aqueous pulp with a mahogany soap, 8. mixture of fatty and resin acids, a fuel oil and a frothing agent, then adding to and mixing with said pulp an alkali, and then subjecting the thus conditioned pulp to a concentration process dependent on the surface characteristics of the ore particles as conditioned.

ERNEST W. GREENE. CHARLES W. HEAD.

CERTIFICATE OF CORRECTION,

Patent No. 2,505,951. December 1, 19m.

ERNEST w. GREENE, ET AL.

, It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, ond column, line 51, and page 2, first column, line 25, after "soap" strike out 011";P Second column, line 11.2, Table II, last column thereof,

for "08.1" read --8.l---; page 5, first column, line 19, Table III, for "Text4 '9" read -Test #9--; and second column, line 21, for "pin oil" read pine oil--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of th case in the Patent Office.

signed and sealed this 19th day of January, A. D. 19145.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

